Loss recovery for the streaming path:
- PLI over signaling: the depacketizer now reports damaged frames
(DepacketizeResult) and the receiver asks the sender for a keyframe
(SessionPli, rate-limited to one per 500 ms). The sender keeps the
signaling channel open during the session and honors PLIs through
the new thread-safe SenderPipeline::request_keyframe(). Recovery
takes one frame time instead of waiting out the GOP.
- RtpJitterBuffer: reorders RTP packets by sequence number (16 packets
/ 60 ms) before the in-order depacketizer, so Wi-Fi reordering is
not misread as loss; in-order streams release immediately, and a
straggler older than the delivered sequence is discarded.
- Hardware H.264 decode probe: DecoderFactory tries h264_v4l2m2m (the
VideoCore path on the Pi) with an automatic software fallback and a
clear journal line for the chosen path; --swdecode opts out.
Validated: PLI end-to-end with a probe that drops a mid-keyframe
packet over real UDP (receiver logged the damaged frame and the PLI
arrived with the session id); hardware probe fails cleanly and falls
back on this desktop; jitter reordering covered by unit tests.
meson test 5/5 in both build configurations, valgrind clean.
fegger